This invention is related to communication methods and devices using electromagnetic waves and has particular application to optical communications in free space. The growing interest in dynamic and rapidly deployable free space optical communication links is combined with efforts to increase traffic throughput, implement sophisticated networking capabilities for intelligent routing of data, and widen the utility of optical terminals. Multi-channel approaches can meet these demands, in particular through the use of wavelength division multiplexing (WDM). There are several advantages to WDM that justify its role in free space optical communications. WDM is well established in the 1.5 μm wavelength band, primarily due to availability of erbium amplifiers, and this wavelength range meets eye safety requirements. Furthermore, the necessary components for WDM already exist and growth in terrestrial communications has driven down their prices. In addition, WDM fiber systems are well understood, and this knowledge relates directly to free space WDM systems.